1. Field of the Invention
The present invention relates to a detecting apparatus, an input apparatus, a pointing device, an individual identification apparatus, and a recording medium, and more particularly to a detecting apparatus, an input apparatus, a pointing device, an individual identification apparatus, and a recording medium that identify individuals by using the natural features and acquired features of their bodies as identification information.
2. Description of the Prior Art
There are conventionally known methods for identifying individuals, used with individual identification apparatuses. Some use, as keys, unchangeable features of a body such as a fingerprint, iris, retina, hand print, and face. Others use, as keys, properties changing with time, such as a voiceprint and signature.
Generally, to use the features of a body such as a fingerprint, iris, retina, hand print, and face as keys, they are in advance measured by a digital camera or the like, and it is determined whether those thus measured match those registered. This is also true for information changing with time, such as a voiceprint and signature; inputted audio information and text information are digitized, and it is determined whether the digitized information matches registered digital information.
In xe2x80x9cUSER AUTHENTICATION METHOD AND USER AUTHENTICATION SYSTEMxe2x80x9d disclosed in Japanese Published Unexamined Patent Application No. Hei 10-269182, a system is proposed which uses the peculiarities of operations of keyboard and mouse buttons to identify individuals with high accuracy. The Japanese Published Unexamined Patent Application No. Hei 10-269182 proposes identifying individuals by patterns obtained based on the peculiarities of operations of keyboard and mouse buttons.
Specifically, in the Japanese Published Unexamined Patent Application No. Hei 10-269182, when a predetermined password is entered, the timings of turning on and off a keyboard are measured, and when mouse buttons are clicked plural times, on/off timings are measured. The obtained timings are converted to binary values to create patterns, which are stored as personal information. An inputted pattern and registered timing patterns are compared to identify individuals.
The method of using the peculiarities of keyboard operations for individual identification is used in, e.g., BIOPASSWORD (http://www.biopassword.com.). Anotherproposedmethodfor identifying individualsuses individual walking patterns.
By the way, it is generally performed in a computer""s access management or the like that the individual identification method as described above is used for user identification at first log-in or connection to a network to determine whether a user is a registered principal or one of plural registered persons.
However, the above-described method used for a computer""s access management cannot prevent the fraud of impersonating authorized users. Specifically, generally, in a computer""s access management, once it has been determined that a user is a registered principal or one of plural registered persons, the lock is unlocked and no subsequent check is made.
In other words, whether the features of a body such as a fingerprint, iris, retina, hand print, and face are used as keys or keyboard operation patterns are used as keys, their measurement subjects are verified only at the first log-in or at the time of connection to a network, and after the verification, they are generally not measured repeatedly.
Consequently, where a principal is away from his seat or an access right is obtained by forging the measurement subjects or other methods, the fraud could freely gain access to secret information.
Also when a voice print or signature changing with time is used, the same problem could occur because it is usually improbable for users to keep uttering their voice or using a pen for the duration of operations of a terminal such as a computer.
The above-described method for identifying individuals by using the features of abodyas keys, which has developed originally for the purpose of identifying one of a large number of candidates, is capable of identifying one of a large number of candidates. However, it is not suitable for determining that a user is a registered principal or one of plural registered persons over time.
The above-described method has a basic problem in that because of the nature of using the features of a body as keys, identification subjects corresponding to the keys are easily forged because they always become identical, so that frauds by forging cannot be completely prevented.
For example, with the method of using a fingerprint, hand print, and face, there is a highly probable risk that they are relatively easily duplicated because it uses appearances. Also with the method of using irises, since iris patterns are scanned by a camera, they could be stolen by the same method.
Although the method of using retinas is resistant to forgery, they may be stolen by some method since the method uses shapes. Voice prints may be stolen by recording them. Signatures may also be stolen since users conduct much training so as to develop constantly stable signature.
Furthermore, once these measurement subjects have been stolen or forged, since principals cannot change measurement subjects such as fingerprints, there is another problem that principals stolen cannot use the measurement subject for individual identification during their lifetime.
These methods have problems as described below. With the method of using fingerprints, users have a strong sense of mental resistance against it because of its image of criminal investigation and therefore there is a difficult problem, independent of technology, that its image must be removed to achieve widespread use. With the method of using blood vessel patterns of retinas, there is a problem in that users suffer from a mental burden because of the need to irradiate eyes with light.
The method of using face shapes lacks stability because of the need to confine postures and illumination conditions within a given range. Voice prints and signatures depend on mental states and health and lack stability. Furthermore, fingerprints, faces, and hand prints may not, in some cases, be used because of accessories such as glasses and finger rings, and appearance change due to makeup or chemical agents, contamination, and the like.
The method of identifying individuals from keyboard operation patterns is applicable only to adequately stable typing patterns such as password entry. As a matter of course, with this method, no information can be obtained from one button operation.
There is not much information that can be obtained from typing patterns alone, produced from a small number of key operations such as password entry, including a double-clicking operation, so that it is impossible to correctly distinguish many persons. Further, the method cannot be used except during specific operations such as text preparation and programming. The accuracy of the method depends greatly on factors such as the level of typing skill, mental states, and health.
As another method for identifying individuals, a method is proposed that uses individual walking patterns. This method can be used for the management of access to buildings or the like but cannot for a computer""s access management.
The present invention has been made in view of the above circumstances and provides a detecting apparatus, an input apparatus, a pointing device, an individual identification apparatus, and a recording medium that use information about users"" bodies, which disables the fraud of impersonating authorized users, and is extremely difficult to forge and is obtained without giving the users a sense of inhibitions, without restraining their bodies during use, and independent of their mental states and health.
According to an aspect of the present invention, the detecting apparatus has a pressed member having a side being pressed with a finger, a detector which detects a feature reflecting a change of a contact state between the finger and the side or a feature reflecting a change of a pressing state with the finger against the side.
Specifically, the movements of a finger when a pressed member (hereinafter referred to as a button) such as keyboard buttons and mouse buttons is pressed can be regarded as changes of a contact state of the finger surface with the side at movement of an approximately vertical direction of the finger with respect to the palm during button operations, that is, at vertical movement of the finger, and as changes of a pressing state such as time displacements of finger positions with respect to the button surface at vertical movement of the finger.
The finger movements depend on peculiarities (acquired features) that are different among individuals, and the size, shape, and flexibility of fingers are governed by individual differences (natural features) Therefore, individuals can be identified by detecting during keyboard typing or during mouse clicking, when a side is pressed, at least one of features reflecting changes of a contact state between a pressing finger and the side, and features reflecting changes of a pressing state of the pressing finger and the side.
According to another aspect of the present invention, the features reflecting changes of a contact state are at least one of a contact area changing with time between the finger and a side when the side is pressed, a finger shape changing with time when the side is pressed, and undulation of the finger surface changing with time when the side is pressed, and the features reflecting changes of a pressing state are at least one of pressing force changing with time when the side is pressed, a pressing amount changing with time to the side when the side is pressed, changes of stress occurring inside a subject when its side is pressed, changes of the speed of finger movement when the side is pressed, and changes of a finger movement position when the side is pressed.
A contact area between the finger and the side when it is pressed changes with time as shown in FIG. 2, for example. The contact area between the finger and a button becomes minimum (S1 and S5) when a finger tip lightly touches the button, increases gradually (from t2 to t3) in proportion to the magnitude of pressing force applied to the button after the button is pressed, and becomes maximum (S3) when the magnitude of pressing force applied to the button becomes maximum (t3). When the button is released, the contact area decreases gradually (from t3 to t4) from the maximum value and returns to standby values (S1 and S5) or zero. Thus, the contact area changes corresponding to the vertical movement of the finger.
The shape of the finger changing with time when the side is pressed also exhibits a similar tendency. For example, as shown in FIG. 3, when the shape of the finger contacting with the side is elliptic, a length change of the long axis l and a length change of the short axis m of the ellipse when a finger presses the side can be detected as physical amounts representing the finger shapes changing with time. In this case, more information can be obtained because the two parameters, the long axis l and the short axis m, are used. Of course, besides measuring actual measurement values themselves of the lengths of the long axis l and the short axis m, a system may be constructed to detect measurement values indirectly reflecting the lengths of the long axis l and the short axis m, such as electrical resistance measurement values by a group of linear or minute electrodes as will be described later.
The time-dependent actual measurement values themselves of undulations such as a fingerprint when the side is pressed, callosity, verruca, and wrinkle on the finger surface and measurement values reflecting the irregularities changing with time can be used as individual identification information because they exhibit the similar tendency.
Changes of pressing force given by the finger (or values reflecting changes of the pressing force) may also be measured. The same curve as that of FIG. 4 can be obtained from changes of pressing force on a contact portion between the finger and a button if the finger tip deforms linearly with respect to the pressing force. Even if not linear, the information is effective as information representing individual differences.
The amount of pressing force changing applied to the side when it is pressed can be obtained as data as shown in FIG. 5, for example. Specifically, the tilts of the curve shown in FIG. 5 indicate the movement speed of a button, the button is pressed downward as time elapses, and where it is sufficiently pressed (ta, t3, tb), a displacement becomes zero, and then the button returns to its original position. Although the shape of the curve depends on the design of a button, even if the same button is used, since the speed and acceleration at which the button is pressed vary among persons, individuals can be identified by differences of curve shapes. It is considered that the individual differences of curve shapes are governed by peculiarities acquired when pressing buttons.
FIG. 6 is a graph of numeric representation of the relationship between button surface positions during button operations of FIG. 2, and contact areas between the button and the finger. Button surface positions, or button pressing force amounts, usually form a proportional relationship with action from the button to the finger. Accordingly, the horizontal axis y of FIG. 6 can be replaced by force acting on the finger (herein, since the position of the button at maximum pressing force is defined as a starting point of 0, acting force F=kxc2x7s(xe2x88x92y), where k is a spring constant).
The relationship between pressing force applied to the finger and a resulting change of a contact area is little influenced by time t. The tilt of the curve is governed by the elasticity of the finger. The elasticity of the finger is considered to be determined by primarily natural elements such as the shape, size, and positional relationship of skin, hypoderma, phalanx, and the like, and the mechanical natures of the respective elasticity and the like, plus acquired elements such as stimuli to the skin, and change of keratin layers due to added age. Specifically, since the acquired elements ordinarily change only a little during a short period of time, they can be used as data representing individual differences and turn into data having high identification accuracy in combination with the natural elements.
At button surface position y3=0 of FIG. 6, a contact area S changes from S3 to Sxe2x80x23 (a curve indicated by a dashed line) when pressing force (hereinafter referred to as overpress) beyond a displacement amount of the button is applied. The period from ta to tb of FIG. 5 is the overpress time. In the curve of FIG. 6, only the curve shape of the overpress portion is primarily produced by differences of individual peculiarities.
The curve of FIG. 5 representing the peculiarities of button pressing operations and the overpress portion curve of FIG. 6 produce some variations for each measurement even for an identical person, while the shape of the curve except for the overpress portion changes little for an identical person so long as the position of a finger with respect to a button is stable. Any information, that is, the curve shape, can be used as identification information because it is different depending on persons, including variations for each measurement.
FIG. 4 shows the relationship between time t and contact area S. The shape of the curve, as apparent from the foregoing description, exhibits a combination of the peculiarities of button pressing speeds (FIG. 5), the peculiarities of overpress (the portion indicated by the dashed line of FIG. 6), and nature features of the finger tip (the solid line of FIG. 6). Accordingly, the curve shape is different depending on persons and can therefore be used as identification information. The dashed line portion with S3xe2x80x2 at its peak between times ta and tb represents a route during overpressing.
Actual measurement values of changes of stress occurring inside a subject when its side is pressed, changes of the speed of finger movement when the side is pressed, and changes of a finger movement position when the side is pressed, and measurement values reflecting these changes can also be used for individual identification because they present physical amounts having the same tendency. By constructing a system so that not only these features are individually detected but also measurement values on a combination of, e.g., a contact area, finger shape, pressing force, button pressing amount, and irregularities on the finger are detected, individual identification data for accurate individual identification is obtained.
These measurement subjects, as described previously, fluctuate within a certain range and change with time because they contain movement peculiarities, unlike body portions not changing in shape such as a fingerprint, hand print, retina and iris. For this reason, information about these measurement subjects provides individual identification data that is extremely difficult to forge or replicate.
An input apparatus according to another aspect of the present invention includes a detecting apparatus set forth in the present invention.
A pointing device according to another aspect of the present invention includes an indication unit that gives indications to a connected equipment when pressing force is applied by a finger, and the indication unit is provided with a detector of a detecting apparatus set forth in the present invention.
The detector of the detecting apparatus detects at least one of features reflecting changes of a contact state between a finger and the side when it is pressed, and features reflecting changes of a pressing state of the pressing finger and the side when it is pressed, and corresponds to, e.g., a measuring part or a measured unit set forth in the present invention.
Furthermore, an individual identification apparatus according to another aspect of the present invention includes a storage part that stores at least one of features reflecting the movements of an individual""s finger, and values obtained by processing the features, and an identification part that identifies individuals based on an inputted feature and storage values stored in the storage part.
Specifically, the individual identification apparatus according to another aspect of the present invention stores, as a storage value for identifying an individual, at least one of features reflecting the movements of an individual""s finger, and values obtained by processing the features, and the identification part determines whether an inputted feature indicates the individual represented by the storage value.
The storage part may store a storage value of one individual or storage values of plural individuals. When the storage part stores a storage value of only one individual, or if the storage part stores storage values of plural individuals and the identification part can judge which individual an inputted feature indicates, the identification part reads one storage value from the storage part, and compares the storage value with the inputted feature to determine whether these represent one identical individual.
If the storage part stores storage values of plural individuals and the identification part cannot judge which individual an inputted feature indicates, the identification part reads all storage values from the storage part and compares all storage values and the inputted feature to determine whether a person matching the inputted feature exists in persons represented by all the storage values.
The identification part, as an example of an identification method, calculates the distance between a read storage value and an inputted feature, and judges as an identical individual if the distance is smaller than a predetermined threshold distance.
According to this method, a matching check can be made to authenticate principals simply by comparing with a threshold distance. As distances to be calculated, distances used in statistical discriminant analysis and cluster analysis, e.g., street distances, Euclidean distances, standardization Euclidean distances, Minkowski distances, Maharanobis distances, and other distances can be used (Behavior Metrics Series xe2x80x9cScience of Truth and Falsehoodxe2x80x9d by Masakatsu Murakami, Asakura Publishing Co., Ltd., 1996). The first four types of distances are obtained as distances between waveform vectors of unknown users and registered feature vectors. Maharanobis distance d2j can be calculated from an expression (1) below, where the average of population of k groups, xcexcj=(xcexc1j, xcexc2j, . . . xcexcpj)xe2x80x2 (j=1, 2, . . . k)xcexcj; an observed value, X=(x1, x2, . . . xp)xe2x80x2; a variance/covariance matrix, xcexa3j; and its inverse matrix, xcexa3jxe2x88x921.
d2j=(Xxe2x88x92xcexcj)xe2x80x2xcexa3xe2x88x921(Xxe2x88x92xcexcj)xe2x80x83xe2x80x83(1)
Maharanobis distance d2j is calculated from a waveform vector of an unknown user, a registered feature vector (average vector), and the inverse matrix of a feature matrix (a variance/covariance matrix or correlation matrix). Since a threshold distance may differ for each registrant, preferably it should be stored in the storage part together with the identification number of a registrant.
An individual identification apparatus according to another aspect of the present invention includes a feature extraction part that extracts features reflecting the feature of finger movements from physical amounts reflecting the movements of a finger pressing a press subject; a storage part that stores at least one of features reflecting the movements of an individual""s finger, and values obtained by processing the features, and an identification part that identifies individuals based on features inputted from the feature extraction part and storage values stored in the storage part.
Specifically, in the individual identification apparatus according to another aspect of the present invention, the feature extraction part extracts features reflecting the feature of finger movements from physical amounts reflecting the movements of a finger pressing a subject to be pressed, and outputs them to the storage part or the identification part.
The storage part stores features outputted from the feature extraction part, and the identification part uses the features outputted from the feature extraction part as the inputted features and compares them with the features read from the storage part to make identification. The storage part and the identification part function like the storage part and the identification part of the individual identification apparatus according to another aspect of the present invention.
The individual identification apparatus according to another aspect of the present invention includes a detection part that detects physical amounts reflecting the movements of a finger pressing a subject to be pressed, a feature extraction part that extracts features reflecting the feature of finger movements from the detected physical amounts, a storage part that stores at least one of features reflecting the movements of an individual""s finger, and values obtained by processing the features, and an identification part that identifies individuals based on the features inputted from the feature extraction part and the features stored in the storage part.
Specifically, in the individual identification apparatus according to another aspect of the present invention, the detection part detects physical amounts reflecting the movements of a finger pressing a press subject and outputs them to the feature extraction part. The feature extraction part extracts features reflecting the feature of finger movements from the physical amounts detected by the detection part and outputs them to the storage part or the identification part. The feature extraction part, the storage part, and the identification part function like the feature extraction part, the storage part, and the identification part of the individual identification apparatus according to another aspect of the present invention.
The individual identification apparatus according to another aspect of the present invention includes a device, a detecting element that detects amounts in accordance with the movements of a part of a body during an operation of the device, a storage part that stores features of plural persons in accordance with the movements of the part of the body before and after the device is operated, a temporary storage part that holds the detection amounts while updating them as required for a predetermined period of time, and an identification part that, when the device is operated, identifies individuals based on the features stored in the storage part, as well as both detection amount before the device is operated, stored in the temporary storage part, and detection amount after the device is operated.
The individual identification apparatus according to another aspect of the present invention, which includes the detection element that detects the movements of a part of a body such as the movements of a finger and the movements of an arm immediately before and after the device is operated, identifies individuals based on features detected in accordance with the movements of the part of the body immediately before the device is operated, and features detected in accordance with the movements of the part of the body immediately after the device is operated, so that features containing information about the movements of the part of a person and other information are obtained, providing much greater accuracy for individual identification.
The individual identification apparatus according to another aspect of the present invention performs processing based on a recording medium recording a program that reads a storage value from the storage part that stores at least one of features reflecting the movements of an individual""s finger and values obtained by processing the features, and identifies individuals based on an inputted feature and the read storage value.
The individual identification apparatus according to another aspect of the present invention may perform processing based on a recording medium recording a program that identifies individuals based on features of plural persons, stored in the storage part, in accordance with the movements of a part of a body before and after the device or switch is operated; and detection amounts before the device is operated, and detection amounts after the device is operated, stored in the temporary storage part that stores detection values in accordance with the movements of the part of individual bodies while updating them as required for a predetermined period of time. The recording medium is recorded in a predetermined recording area.